The 25-year-old son of Marian (60) and William 'Billy' Horgan (67), was arrested at the scene at Murmount Avenue, Montenotte in Cork shortly after 8am.

Marian and Billy Horgan were devoted to each other; they had three children. Photo: ProvisionForensic investigators at the scene of the attack in Montenotte, Cork. Photo: Michael Mac SweeneyThe scene of this morning's tragedy. Inset: Marian and Billy Horgan

A group of neighbours, one of whom armed himself with a hurley, ran to the aid of Mr Horgan after his son Paul walked out of the house in a very agitated state with traces of blood on his clothing.

It is understood Paul told one shocked local: "I've just done a very bad thing."

Neighbours became concerned when the young man got very distressed and resisted being questioned about what was wrong.

Garda at the scene this morningMurmont Avenue in Cork where the incident happened

Three men, one armed with a hurley, eventually had to physically restrain the young man by sitting on him while another local went into the house to investigate what was wrong.

Ms Horgan was found lying critically injured in a pool of blood while her husband was bleeding profusely from a head wound. He was desperately trying to help his wife. One man who witnessed the scene was so upset he ran out of the house and got ill.

A local who helped Mr Horgan said they were advised not to comment on the tragedy.

"I've nothing to say. I'll do my talking to the gardaí," he said.

Another relative of Mr Hogan declined to comment, saying the family was "too upset to say anything".

Despite the prompt attendance of gardaí and paramedics, Ms Horgan's condition could not be stabilised and she was pronounced dead at the scene.

Her husband, who was bleeding profusely from multiple stab wounds to his head and arms, was rushed to Mercy University Hospital.

His injuries were described as primarily defensive in nature and are not believed to be life- threatening.

Mr Horgan underwent emergency surgery yesterday and is expected to make a full recovery.

Tragedy

However, it will be 24 to 48 hours before he will be able to speak to detectives about the sequence of events that led to the tragedy.

Paul Horgan was arrested under Section 4 of the Criminal Justice Act, 1984, and taken to Mayfield Garda Station for questioning. He can be questioned for an initial period of 12 hours but this can be extended further.

Gardaí stressed that the nature of their investigation will now be determined by the post mortem examination findings.

Assistant State Pathologist Dr Margaret Bolster conducted a preliminary examination of the scene from 11.30am.

The body of Ms Horgan was then transferred to Cork University Hospital at 1pm for the post mortem examination.

Garda technical experts continued a detailed forensic analy­sis of the semi-detached house and the roadway outside.